WASHINGTON (Reuters) – Eight lawmakers urged President Barack Obama’s administration on Wednesday to broaden the scope of proposed duties on billions of dollars of solar panels from China, as the U.S. government nears its final rulings in the case.

The lawmakers, led by Oregon Democratic Senators Ron Wyden and Jeff Merkley, criticized an earlier Commerce Department decision to exclude Chinese solar panels containing cells made in another country from preliminary duties of more than 30 percent.

They argued that would allow Chinese solar panel producers to escape U.S. duties by outsourcing cell production to another country, even if the materials for the cells come from China and the final solar panels are assembled there.

“This would appear to undermine the intent of the petition that was filed by the U.S. industry, and invite the circumvention of the anti-dumping and countervailing duty orders,” the lawmakers said.

SolarWorld America, an Oregon-based subsidiary of Germany’s SolarWorld AG, has led the drive for the United States to impose duties on Chinese-made solar products, which it says are unfairly priced and subsidized.

SolarWorld is also behind a push in Europe for duties on Chinese solar products.

The U.S. Commerce Department is scheduled to release its final determinations in the case on October 10. A department official said on Wednesday the agency would re-examine the question of how widely to apply any duties.

A separate agency, the U.S. International Trade Commission, has the final word on whether duties are applied. The date for that vote has not been announced, but typically occurs shortly after the final Commerce Department determination.

The trade panel will hold a hearing on the solar case on October 3. It must decide whether U.S. producers have been materially injured, or are threatened with material injury, by the lower-priced Chinese product for the final duties to go into force.

Companies have been required to post bonds or cash deposits based on the earlier preliminary duty rates. Those will be refunded if no injury is found.